Posted
by
samzenpus
on Thursday March 28, 2013 @06:15PM
from the little-flyer dept.

yyzmcleod writes "Building on the work of last year's bionic creation, the Smart Bird, Festo announced that it will literally launch its latest creation, the BionicOpter, at Hannover Messe in April. With a wingspan of 63 cm and weighing in at 175 grams, the robotic dragonfly mimics all forms of flight as its natural counterpart, including hover, glide and maneuvering in all directions. This is made possible, the company says, by the BionicOpter's ability to move each of its four wings independently, as well as control their amplitude, frequency and angle of attack. Including its actuated head and body, the robot exhibits 13 degrees of freedom, which allows it to rapidly accelerate, decelerate, turn and fly backwards."

I was under the impression that a control system implies a closed loop or feedback mechanism i.e. a system that measures the current state, and decides an actuation mechanism to get to where it wants to go. Do they mean autonomous and non-autonomous modes instead?

Probably not. It may mean that there's modes based on pre-programmed wing flap timings. It may also mean that there's hidden variables regarding the craft's real world state that the engineers have to guess at with sensors rather than know for certain.

I was under the impression that a control system implies a closed loop or feedback mechanism

Feedback is a great way to stabilise a system, but it is not essential. A stepper motor - even a precise one, like the one in your watch - does not require readback from a position encoder to function. Digital audio amplifiers do not need negative feedback in order to achieve proper linearity, like analogue amplifiers do.

Sometimes it is desirable to do without feedback. The auto-focus mechanism in a professional camera operates without feedback in order to work at the highest possible speed. The lens motor and AF sensor are carefully calibrated so that focus is achieved in a single measurement-movement cycle. This is faster than making multiple measurements, which requires the lens motor to be stopped during each measurement. Feedback is only used to confirm autofocus success, and trigger a second attempt in case of failure.

But if you don't have feedback, what do you mean by a 'control-system'? An open loop control system would be like a look-up table or something: decide apriori what you want to do, and then apply the pre-computed action without any measurements or correction system. But then, there really isn't a control-system, because it doesn't account for errors (the only way to know if there are errors is via measurements, which constitutes feedback).

Very nice. Festo, which is a German industrial robotics firm, does a technical tour de force every year. They built a robotic bird [youtube.com] two years ago. In 2009, they built a robot penguin" which swims beautifully.

Festo does this to sell their industrial robotics systems, which are very well made.

While angle of attack is accurate in describing rotor action, it's more commonly used to describe the angle at which a craft's nose cuts into the wind to offset the angle of sideslip in determine a heading.

I've never heard angle of attack described that way. It's always described as the angle of the chord of the wing relative to the direction of the airflow - the pitch of the wing, not the yaw of the aircraft.

It should be noted that while helicopters can do all of these things, it really isn't that good at it. Hovering is actually quite a stress inducing activity, and most helicopters will completely avoid this as much as possible. This could in theory create a viable alternative that could be run with a simple up/down, turn, and movement interface.